Issue link: https://resources.mouser.com/i/1313800
In spatial multiplexing, each spatial channel carries independent information (Figure 4). If the environmental scattering is rich enough, many independent sub-channels are created in the same allocated bandwidth, thus achieving multiplexing gains with no additional cost in bandwidth or power. The multiplexing gain is also referred to as degrees of freedom in reference to the signal space constellation; in a massive-MIMO configuration, the degrees of freedom govern the overall capacity of the system. 3 With massive MIMO, multiple antennas focus the transmit and receive signals into smaller regions of space, bringing huge improvements in throughput and energy efficiency. The more data streams, the greater the data rate and more efficient use of radiated power. This approach also improves link reliability. The increase in antennas means more degrees of freedom that can be spent on spatial diversity. It improves selectivity in the transmit and receive data streams and enhances interference cancellation. Massive MIMO will provide benefits, including: • Preventing transmission in undesired directions, alleviating interference • Decreasing latency, allowing for faster speeds and higher reliability • Reducing fading and drops, boosting signal-to-noise-ratio (SNR) • Increasing spectral efficiency and high reliability • Greater energy efficiency 5G Massive MIMO and Sub-6GHz Deployment It's clear that to achieve the 5G target of 20Gb/s data rates, it will be necessary to use millimeter-wave (mmWave) spectrum. However, several key challenges must be addressed before mmWave can truly be used for mobile communications. While operators and original equipment manufacturers (OEMs) continue working to finalize mmWave technology, sub-6GHz will be the go-to 5G network technology in the near term. Sub-6GHz frequencies are suited for both rural and urban areas since the technology can deliver high data rates over long distances (Figure 5). Operators are initially expected to deploy 5G in 3,300 to 4,200MHz and 4,400 to 5,000MHz frequency ranges, which will allow up to 100MHz channel bandwidths. | 24 | Figure 4: Each channel involved in spatial multiplexing with massive MIMO carries independent information.